From: Bas van Dijk
Hello,
(This should actually be a reply to the "Move MonadIO to base" thread[1] but I didn't want to break up the extremely interesting discussion on the MonadTransMorph class)
Would it be useful if we got rid of MonadIO:
class (Monad m) => MonadIO m where liftIO :: IO a -> m a
and replace it with the generalization:
class (Monad m, Monad n) => MonadBase m n | m -> n where inBase :: n a -> m a
which would allow lifting not just IO but any base monad into a stack of monad transformers.
I personally wouldn't find this particularly useful. Nearly all of my monadic programming (i.e. everything that comes to mind) uses one of three types of monads: 1. IO 2. ST 3. Monad transformers stacked on IO Lifting functions are only useful in the third case, and then I only need "lift" and "liftIO". I do like the idea and I'm not opposed to the suggestion, I just don't see a use for it myself. John